Design of an ultrafast electron diffractometer with multiple operation modes

2021 ◽  
Author(s):  
Chun-Long Hu ◽  
Zhong Wang ◽  
Yi-Jie Shi ◽  
Chang Ye ◽  
Wen-Xi Liang
Robotica ◽  
2014 ◽  
Vol 32 (7) ◽  
pp. 1171-1188 ◽  
Author(s):  
Xiuyun He ◽  
Xianwen Kong ◽  
Damien Chablat ◽  
Stéphane Caro ◽  
Guangbo Hao

SUMMARYThis paper presents a novel one-degree-of-freedom (1-DOF) single-loop reconfigurable 7R mechanism with multiple operation modes (SLR7RMMOM), composed of seven revolute (R) joints, via adding a revolute joint to the overconstrained Sarrus linkage. The SLR7RMMOM can switch from one operation mode to another without disconnection and reassembly, and is a non-overconstrained mechanism. The algorithm for the inverse kinematics of the serial 6R mechanism using kinematic mapping is adopted to deal with the kinematic analysis of the SLR7RMMOM. First, a numerical method is applied and an example is given to show that there are 13 sets of solutions for the SLR7RMMOM, corresponding to each input angle. Among these solutions, nine sets are real solutions, which are verified using both a computer-aided design (CAD) model and a prototype of the mechanism. Then an algebraic approach is also used to analyse the mechanism and same results are obtained as the numerical one. It is shown from both numerical and algebraic approaches that the SLR7RMMOM has three operation modes: a translational mode and two 1-DOF planar modes. The transitional configurations among the three modes are also identified.


2020 ◽  
Vol 20 (3) ◽  
pp. 675-686
Author(s):  
Yaoqiang Wang ◽  
Guanyu Du ◽  
Jun Liang ◽  
Ming Qin

Author(s):  
Xianwen Kong

Parallel manipulators (PMs) with multiple operation modes are novel reconfigurable PMs which use less number of actuators and can be reconfigured without disassembly. Although several classes of PMs with multiple operation modes that have the same DOF (degrees-of-freedom) in all the operation modes have been proposed, only one class of variable-DOF PMs with multiple operation modes — PMs with multiple operation modes that do not have the same DOF in all the operation modes — have been proposed so far. This paper deals with the type synthesis of variable-DOF PMs with both planar and 3T1R (or Schönflies motion which has three translational DOF and 1 rotational DOF) operation modes. The axes of rotation of the moving platform in the planar operation mode are not parallel to the axes of rotation of the moving platform in the 3T1R operation mode. At first, an approach to the type synthesis of PMs with multiple operation modes is recalled. Based on the results on the type synthesis of planar PMs and 3T1R PMs, the types of variable-DOF PMs with both planar and 3T1R operation modes are then obtained. This work can be extended to the type synthesis of other classes of PMs with multiple operation modes.


Author(s):  
Shota Sasaki ◽  
Kentaro Hirata ◽  
Yoichiro Masui ◽  
Masahiro Samei ◽  
Akihiro Kawasaki ◽  
...  

Author(s):  
Xianwen Kong ◽  
Cle´ment M. Gosselin ◽  
Pierre-Luc Richard

There are usually several motion patterns having the same DOF (degree of freedom). For example, planar motion, spherical motion, and spatial translation are motion patterns with 3-DOF. An f-DOF parallel mechanism with multiple operation modes is a parallel mechanism that can generate different motion patterns with f DOF. Up to now, no method has been proposed for the type synthesis of parallel mechanisms with multiple operation modes. This paper presents a general method for the type synthesis of parallel mechanisms with multiple operation modes. Using the proposed approach, 3-DOF parallel mechanisms with both spherical and translational modes, i.e., parallel mechanisms generating both the spherical motion pattern and the spatial translational motion pattern, are generated systematically. A large number of parallel mechanisms with both spherical and translational modes are obtained.


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